4Fes - 3O2g - 2 Fe2O3sFor the following reaction- - S - -549-4 J K-1 mol-1 at 298 K- -rH- - -1648 - 103 J mol-1The reaction is spontaneous

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Second Law of Thermodynamics

4Fes + 3O2g →...

Question

$4 F e (s) + 3 O_{2} (g) \to 2 F e_{2} O_{3} (s)$
For the following reaction, $Δ S = - 549.4 J K^{- 1} m o l^{- 1}$ at 298 K. $Δ_{r} H^{⊖} = - 1648 \times 103 J m o l^{- 1}$
The reaction is spontaneous

True

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False

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Solution

The correct option is A True
One decides the spontaneity of a reaction by considering $Δ S_{T o t a l} (Δ S_{s y s} + Δ S_{s u r r})$ . For calculating $Δ S_{s u r r}$ , we have to consider the heat absorbed by the surroundings which is equal to $- Δ_{r} H^{⊖}$ . At temperature T, entropy change of the surrounding is
$Δ S_{s u r r} = - \frac{Δ_{r} H^{⊖}}{T}$ (at constant pressure)
$= - \frac{(- 1648 \times 10^{3} J m o l^{- 1})}{298 K}$
$= 5530 J K^{- 1} m o l^{- 1}$
Thus, total entropy change for this reaction
$Δ_{r} S_{t o t a l} = 5530 J K^{- 1} m o l^{- 1} + (- 549.4 J K^{- 1} m o l^{- 1})$
$= 4980.6 J K^{- 1} m o l^{- 1}$
This shows that the above reaction is spontaneous.

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Similar questions

4 F e (s) + 3 O_{2} (g) \to 2 F e_{2} O_{3} (s)

For the following reaction,

Δ S = - 549.4 J K^{- 1} m o l^{- 1}

at 298 K.

Δ_{r} H^{⊖} = - 1648 \times 103 J m o l^{- 1}

The reaction is spontaneous

For oxidation of iron,

4 F e (s) + {3 O}_{2} (g) \to 2 {F e}_{2} O_{3} (s)

entropy change is - 549.4

{J K}^{- 1} {m o l}^{- 1}

at 298 K. In spite of negative entropy change of this reaction, why is the reaction spontaneous?

(

△, H^{⊝}

for this reaction is

- 1648 \times 10^{3} J {m o l}^{- 1}

)

P (g) + 2 Q (g) \to P Q_{2} (g); Δ H = 18 k J m o l^{- 1}

The entropy change of the above reaction

(Δ S_{s y s t e m}) i s 60 J K^{- 1} m o l^{- 1}

At what temperature, the reaction becomes spontaneous?

For a reaction at $25^{\circ} C$ enthalpy change $(△ H)$ and entropy change $(△ S)$ are $- 11.7 \times 103 J m o l^{- 1}$ and $- 105 J m o l^{- 1} K^{- 1}$ respectively. Find out whether this reaction is spontaneous or not?

For a reaction at $25^{\circ} C$ enthalpy change ( $△ H$ ) and entropy change ( $△ S$ ) are -11.7 K J $m o l^{- 1}$ and -105 J $m o l^{- 1}$ $K^{- 1}$ , respectively. It is a spontaneous reaction

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4Fe(s)+3O2(g)→2Fe2O3(s) For the following reaction, ΔS=−549.4 J K−1 mol−1 at 298 K. ΔrH⊖=−1648×103 J mol−1 The reaction is spontaneous

$4 F e (s) + 3 O_{2} (g) \to 2 F e_{2} O_{3} (s)$
For the following reaction, $Δ S = - 549.4 J K^{- 1} m o l^{- 1}$ at 298 K. $Δ_{r} H^{⊖} = - 1648 \times 103 J m o l^{- 1}$
The reaction is spontaneous